1. Field of Invention
The present invention relates to a display device, and particularly to a display device with repair lines.
2. Description of the Related Art
In the past, display devices equipped with cathode ray tube (CRT) had drawbacks such as bulky, heavy, high-radiation, lower definition and so on. To overcome such problems, novel flat panel display technologies have been constantly developed. These newly developed flat panel displays are advantageous as they are light, slim, electricity-saving, low-radiation, full color, etc. These flat panel display devices include liquid crystal display (LCD) devices, plasma display panel (PDP) devices and organic electroluminescent display (OELD) devices. Among these flat panel display devices, the most outstanding and popular one is LCD device, which is counted as the most mature in terms of technology and has widespread applications in handsets, digital cameras, digital video cameras (DVs), personal digital assistants (PDAs), LCD TV sets and so on.
Although the technology of LCD devices is almost fully developed today, some defects are still unavoidable during the manufacturing process. During displaying images on an LCD, these defects will make a viewer feel uncomfortable. If the LCDs with defects are discarded, the production cost would be increased enormously. Generally speaking, it is very difficult to achieve defect-free rate by means of only improving the manufacturing technology. In other words, to advance a defect-repairing technology in LCD panel production is critically important. In prior art, a repair method of LCD panels includes laser welding and laser cutting. However, in consideration of practical wiring designs of LCD panels, not each of open-lines is able to be repaired quickly; some open-lines are even not repairable.
FIG. 1 is a schematic structure diagram of an LCD device. Referring to FIG. 1, an LCD device 100 includes an LCD panel 110, a data control circuit board 120, a scan control circuit board 130, a plurality of data drivers 140 and a plurality of scan drivers 150. The LCD device 100 has a plurality of data lines 112, a plurality of scan lines 114 and a repair line 116. The plurality of data drivers 140 is disposed between the data control circuit board 120 and the LCD panel 110 and is electrically connected to the data control circuit board 120 and the plurality of data lines 112 of the LCD panel 110. The plurality of scan drivers 150 is disposed between the scan control circuit board 130 and the LCD panel 110 and is electrically connected to the scan control circuit board 130 and the plurality of scan lines 114 of the LCD panel 110. It can be seen from FIG. 1, the data drivers 140 and the scan drivers 150 are TAB packages.
The data signal of displayed images are delivered by the data control circuit board 120 to the data drivers 140 first, followed by sending the signal to the data lines 112 while the scan signal of displayed images are delivered by the scan control circuit board 130 to the scan drivers 150 first, followed by sending a scan signal to the scan lines 114. By means of the scan lines 114 to deliver the scan signal of displayed images to active components (not shown in the figure) of the LCD panel 110 and by means of the data lines 112 to deliver the data signal of displayed images to pixel electrodes (not shown in the figure) corresponding to the active components, the LCD panel 110 is able to achieve the display function.
After an LCD panel 110 is fabricated, usually a so-called “cell test” will be carried out to check whether any defects occur on the LCD panel 110 or not. Once a disconnection defect is revealed on the LCD panel 110, a repair line 116 on the LCD panel 110 is used for repairing. For example, when a data line 112 on the LCD panel 110 is damaged, a laser welding process is performed at two welding points 116a and 116b for electrically connecting the repair line 116 and the damaged or broken data line 112, so that most of the functions of the damaged data line 112 can be restored by the repair line 116. Another cell test on the LCD panel 110 will be performed to secure the disconnection defect is repaired. However, since the trend for panel size is bigger and bigger and the resolution is higher and higher, a repair line 116 must be long enough to pass across more and more data lines 112; a too long repair line 116 leads to a parasitic capacitance and too larger resistance therewith. When a signal is transmitted through a long conductive wire, signal attenuation will occur resulting in poor displaying images of the LCD panel 110.
FIG. 2A is a schematic structure diagram of another LCD device capable of improving signal attenuation with the LCD device 100 in FIG. 1. Referring to FIG. 2A, the LCD device 200 is disclosed in an embodiment in U.S. Pat. No. 6,525,705. The LCD device 200 includes an LCD panel 210, a data control circuit board 220, a scan control circuit board 230, a plurality of data drivers 240 and a plurality of scan drivers 250. The LCD device 200 has a plurality of data lines 212, a plurality of scan lines 214 and a first repair line 216 and a second repair line 218. The data control circuit board 220, the data drivers 240 and the scan drivers 250 are the same as those of the LCD device 100, i.e. the data control circuit board 120, the data drivers 140 and the scan drivers 150 of the LCD device 100. The scan control circuit board 230 has a third repair line 232 and an amplifying circuit 234. The amplifying circuit 234 is electrically connected to the third repair line 232 and disposed on the path of the third repair line 232. Besides, the third repair line 232 is electrically connected to the first repair line 216 and the second repair line 218 through the TAB packages.
When a damaged data line 212 on the LCD panel 210 is found, a laser welding is performed at two welding points 216a and 218a for electrically connecting the damaged data line 212 to the first repair line 216 and the second repair line 218, respectively. When the LCD panel 210 is bonded with the data control circuit board 220 and the scan control circuit board 230, a so-called “bonding process” is accomplished. At this time, the damaged data line 212 is able to perform most of the functions by means of the first repair line 216, the third repair line 232 and the second repair line 218. Since an amplifying circuit 234 is disposed on the path of the third repair line 232, the signal delivered by the third repair line 232 is amplified by the amplifying circuit 234, so that the signal attenuation due to transmission along a long distance of the repair line 218 is reduced. However, due to limited driving powers of the data drivers 240 and the scan drivers 250, the scheme is limited and not capable of solving the attenuation problem of the signal delivered by the repair lines 216 and 232 to meet the modern trend, where newly lunched panels have bigger and bigger screen and higher and higher resolution and therefore the parasitic capacitances of the repair lines 216 and 218 are larger and larger.
There are other conventional LCD panels with repair designs except for the above-described LCD devices 100 and 200. FIGS. 2B and 2C are schematic structure diagrams of two further LCD devices, both of which are able to eliminate the above-described signal attenuation problem. Referring to FIGS. 2B and 2C, the LCD devices 200′ and 200″ in FIGS. 2B and 2C are variations of the LCD device 200. The repair lines 222′ and 222″ on the data control circuit boards 220′ and 220″ are designed in subsection mode, by which the parasitic capacitances of the repair lines 222′ and 222″ are reduced and the open-line defects of the LCD panels 210′ and 210″ of the LCD devices 200′ and 200″ are repaired. The new problem herein is that the repaired LCD panels 21 0′ and 210″ of the LCD devices 200′ and 200″ are not able to be examined for whether the defects are fixed or not in the following cell test. Another problem is that such subsection mode design requires an additional successive process for connecting the repair lines on the data control circuit boards 220′ and 220″, which leads to an increase of production cost and time of the successive processes.